One of the most important parts of the software development process is the process of debugging. Debugging refers to the process of identifying and eliminating errors within a software program. A debugging application program, called a debugger, provides tools to assist a programmer in locating and correcting program errors. For instance, most debuggers provide tools for stepping through the executing code of a program, monitoring the status of input/output (“I/O”) ports, and for monitoring and modifying the contents of memory locations and central processing unit (“CPU”) registers.
Traditionally, a debugger must be run directly on the computer system that is executing the software that is being debugged. This, however, greater hinders the software debugging process because the programmer performing the debugging must be in close proximity to the system being debugged. Other systems allow the debugging of one computer (the “target computer”) through another computer (the “host computer”) connected via an in-target probe (“ITP”). An ITP interfaces to the host computer and the target computer and utilizes a debugging program on the host computer to control the operation of code executing on the target computer. Through the ITP, the execution of program code executing on the target computer can be stepped through, the values of CPU registers and I/O ports can be read and written, and other debugging functions can be performed. An ITP is frequently used to debug system firmware, such as a basic input/output system (“BIOS”) or extensible firmware interface (“EFI”), where an operating system is not available on the target system to execute a debugging program.
While current debugging programs and ITP packages make it easy to stop, start, and step through the execution of program code, current solutions do not provide a convenient solution for stopping program execution at an arbitrary point. Programmers currently utilize an instruction that causes the processor to enter an infinite loop at the desired breakpoint. On the AMD/INTEL processor platform, this instruction is the “JMP $” instruction. While use of the “JMP $” instruction does allow program execution to be halted at a specified point in the execution of the program, use of this instruction is very inconvenient. In particular, use of this instruction is very inconvenient in the debugging of BIOS programs because a new BIOS must be programmed (also referred to herein as “flashing”) each time a “JMP $” instruction is to be added or removed from the program code. Moreover, the programmer must manually restart execution of the program at the instruction that immediately follows the “JMP $” in order to continue program execution. This process can be extremely time consuming for a BIOS programmer.
It is with respect to these considerations and others that the present invention has been made.